Intraoperative neuromonitoring in cervical degenerative spine surgery: a meta-analysis of its impact on neurological outcomes

Abstract

The role of intraoperative neuromonitoring (IONM) in cervical degenerative spine surgery remains controversial, despite its established use in tumor and deformity surgeries. Although IONM is believed to mitigate neurological complications, its effectiveness in degenerative cervical surgery remains inconclusive. Our meta-analysis aimed at systematically reviewing studies comparing neurological outcomes in degenerative cervical spine surgeries performed with and without IONM. A comprehensive search of several databases, including PubMed, Cochrane, Scopus, and Embase was conducted from January 1st, 2000 until July 16th, 2024. The included articles consisted of randomised controlled trials (RCTs), prospective and retrospective cohort studies, and case-control studies. Seven studies including 187.162 patients, with 21.686 undergoing surgery with IONM and 165.476 without it, met inclusion criteria. The pooled analysis showed no statistically significant protective effect provided by IONM (OR = 0.90 [0.51-1.59]; p-value = 0.7140; τ² = 0.3817; I^2 = 80.4%). The significance of the results has been further evaluated through two sensitivity analyses: the former excluding articles based on encoded databases (OR = 1.09 [0.04-32.72]; p-value = 0.9626; τ² = 4.9524; I^2 = 80.3%), the latter removing articles whose heterogeneity substantially influenced the overall variance (OR = 0.72 [0.50-1.05]; p-value = 0.0880; τ² = 0.0242; I^2 = 38.5%). However, both analyses resulted in no significant outcomes. Additionally, a subgroup analysis and univariate meta-regression revealed that sample size (R² = 48.11%) significantly explains heterogeneity across studies, while the use of EMG alongside SSEP and MEP also emerged as a potentially protective approach (OR = 0.39 [0.20-0.79]). The pooled analysis showed no statistically significant effect of intraoperative neuromonitoring in reducing the post-operative complication rate in the context of degenerative cervical spine surgery. However, IONM has become a standard practice, often prompting surgeons to adjust intraoperative procedures or modify pharmacological or anaesthesiologic management in response to alerts, potentially benefiting the patient. While the decision to utilize IONM finally belongs to the surgeon depending on each case, additional research, including large-scale prospective studies, is recommended to clarify the benefits of IONM and to refine standardized guidelines for its use.

Keywords: Cervical spine; Degenerative; Intraoperative neuromonitoring; Neurological outcomes; Spine surgery.